1. Technical Field
The present invention relates to a technology for masking a partial area of a picture to be displayed on a camera screen to protect privacy thereof in a surveillance camera system which enables to control a PAN rotation (horizontal swing), a TILT rotation (vertical swing) and a zooming.
A term “corner” means “corner point” in this specification.
2. Description of Background Art
A surveillance camera system which enables to control a PAN rotation, a TILT rotation and a zooming has a structure in which a surveillance camera capable of a zooming thereof is mounted on a rotative table for a camera capable of rotating freely in a PAN rotational direction and a TILT rotational direction. The system is able to select any picture to be displayed by controlling the rotative table and a zoom mechanism of the surveillance camera via a remote operating device. In general, the system has a sequence control function for taking pictures sequentially in each of directions every preset time interval which directions have been settled beforehand, and an alarm function for pointing immediately toward an area in which something unusual has detected by a motion sensor disposed in a territory to be surveilled, and so on. In case that such a system is set in a public space like a street, a masking process is needed for some part of a picture which should not be taken, for example, a private house or an object prohibited from taking a picture in order to protect privacy.
The patent document 1 (JP, 2007-129336,A) discloses the following. Two representative corners are selected from among corners indicating an area to be protected from being displayed on a 2-dimensional camera screen to protect a privacy thereof, and an information of differences between each of the remained corners and the representative corners are calculated in a 2-dimension, and then memorized. Next, the representative corners are disposed in a 3-dimensional rectangular coordinate system to carry out a PAN rotation, a TILT rotation and a zooming. After that, positions of the representative corners in the 3-dimensional rectangular coordinate system are calculated, and these positions are converted back into a 2-dimensional coordinate system on the camera screen. And the positions of the remained corners are calculated by using the previously memorized information of differences, whereby a processing period time can be reduced.